Process for the manufacturing of surface elements

ABSTRACT

Processes for manufacturing surface elements are provided. The surface elements can include a decorative upper layer and a supporting core. Processes for manufacturing such surface elements can comprise manufacturing a supporting core having a format essentially equaling the desired end user format and provided with an upper side and a lower side, providing a ground coating on the supporting core, and applying a digitally printed décor comprising inks of at least four colors directly on top of the ground coating by means of an ink-jet type printer, said four colors comprising one or more colors different from cyan, magenta, yellow and black; said digitally printed décor being one of wood or mineral, and providing and curing an at least partly translucent wear layer on the upper side of the supporting core.

CROSS REFERENCE TO RELATED APPLICATIONS

This application is a continuation of and claims priority benefits toco-pending U.S. patent application Ser. No. 14/938,108, filed Nov. 11,2015, which is a continuation of and claims priority to U.S. patentapplication Ser. No. 14/531,626, filed Nov. 3, 2014, now U.S. Pat. No.9,321,299, which is a continuation of and claims priority to U.S. patentapplication Ser. No. 13/974,850, filed Aug. 23, 2013, now U.S. Pat. No.8,950,138, which is a continuation of and claims priority benefits toco-pending U.S. patent application Ser. No. 13/467,830, filed May 9,2012, now U.S. Pat. No. 8,944,543, which is a continuation of and claimspriority benefits to co-pending U.S. patent application Ser. No.10/440,317, filed May 19, 2003, which is a divisional application of andclaims priority benefits to U.S. patent application Ser. No. 09/718,398,filed Nov. 24, 2000, now U.S. Pat. No. 6,565,919, which claims prioritybenefits to Swedish Patent Application No. 9904781-3, filed Dec. 23,1999. The entire contents of the above-referenced U.S. patentapplications, U.S. patents, and Swedish patent application are herebyincorporated by reference herein.

TECHNICAL FIELD

The present invention relates to a process for the manufacturing ofsurface elements with a decorative upper surface of which the decorativeelements have a considerably improved matching of the décor betweenadjacent surface elements.

BACKGROUND

Products clad with thermosetting laminate are common in many areasnowadays. They are mostly used where the demands on abrasion resistanceare high, and furthermore where resistance to different chemicals andmoisture is desired. As examples of such products floors, floorskirtings, table tops, work tops and wall panels can be mentioned.

The thermosetting laminate most often consist of a number of base sheetswith a decor sheet placed closest to the surface. The decor sheet can beprovided with a pattern by desire. Common patterns usually visualizedifferent kinds of wood or mineral such as marble and granite.

One common pattern on floor elements is the rod pattern where two ormore rows of rods of, for example wood, is simulated in the decor.

The traditional thermosetting laminate manufacturing includes a numberof steps which will result in a random matching tolerance of up to ±5mm, which is considered too great. The steps included in themanufacturing of a laminate floor is; printing decor on a paper ofα-cellulose, impregnating the decorative paper withmelamine-formaldehyde resin, drying the decorative paper, laminating thedecorative paper under heat and pressure together with similarly treatedsupporting papers, applying the decorative laminate on a carrier andfinally sawing and milling the carrier to the desired format. All thesesteps in the manufacturing will cause a change in format on the decorpaper. It will therefore be practically impossible to achieve a desiredmatch of patterns between the elements of a without causing greatamounts of wasted laminate. The thermosetting laminate is a rathercostly part of a laminate floor.

SUMMARY

It has, through the present invention, been made possible to overcomethe above mentioned problems and a surface element with a decorativesurface where the decorative pattern between different surface elementsis matching has been obtained. The invention relates to a process forthe manufacturing of surface elements which comprises a decorative upperlayer and a supporting core. The surface elements may be used as floor,wall or ceiling boards. The invention is characterized in that;

-   i) A supporting core with a desired format is manufactured and    provided with an upper side and a lower side.-   ii) The upper side of the supporting core is then provided with a    décor, by for example printing. The décor is positioned after a    predetermined fixing point on the supporting core.-   iii) The upper side of the supporting core is then provided with a    protecting, at least partly translucent, wear layer by for example    spray coating, roller coating, curtain coating and immersion coating    or by being provided with one or more sheets of α-cellulose    impregnated with thermosetting resin or lacquer.

The décor is suitably achieved by digitization of an actual archetype orby partly or completely being created in a digital media. The digitizeddécor is stored digitally in order to be used as a control function andoriginal, together with possible control programs, when printing thedécor.

The décor may accordingly be obtained by making a high resolution orselected resolution digital picture of the desired décor. This issuitably made by means of a digital camera or scanner. The most commondécor will of course be different kinds of wood and minerals likemarble, as these probably will continue to be preferred surfacedecoration in home and public environments. It is, however, possible todepict anything that is visible. The digitized version of the décor isthen edited to fit the size of the supporting core. It is also possibleto rearrange the décor in many different ways, like changing colortones, contrast, dividing the décor into smaller segments and addingother decorative elements. It is also possible to completely create thedécor in a computer equipped for graphic design. It is possible tocreate a simulated décor so realistic that even a professional will havegreat problems in visually separating it from genuine material. Thismakes it possible to make for example floor boards with an almostperfect illusion of a rare kind of wood, like ebony or rose wood andstill preserving trees under threat of extermination.

The digital décor is used together with guiding programs to control aprinter. The printer may be of an electrostatic type or an ink-jet typeprinter. Most often the colors yellow, magenta, cyan and black will besufficient for the printing process, but in some cases it might beadvantageous to add white. Some colors are difficult to achieve usingthe colors yellow, magenta, cyan, black and white whereby the colorslight magenta and light cyan may be added. It is also possible to add socalled spot colors where specific color tones are difficult to achieveor where only certain parts of the color spectrum with intermixingshades is desired. The resolution needed is much depending on the décorthat is to be simulated, but resolutions of 10-1500 dots per inch (dpi)is the practical range in which most décors will be printed. Undernormal conditions a resolution of 300-800 dpi is sufficient whencreating simulations of even very complex decorative patterns and stillachieve a result that visually is very difficult to separate from thearchetype without close and thorough inspection.

The digitally stored décor can also be used together with supportprograms when guiding other operations and procedures in themanufacturing process. Such steps in the operation may includeprocedures like identification marking, packaging, lacquering, surfaceembossing, storing and delivery logistics as well as assemblyinstructions.

It is advantageous to manufacture the supporting core in the desired enduser format and to provide it with edges suited for joining beforeapplying the décor and wear layer, since the amount of waste thereby isradically reduced. The décor matching tolerances will also be improvedfurther by this procedure.

The main part of the supporting core is suitably constituted by aparticle board or a fiber board. It is, however, possible to manufacturethe core that at least partly consist of a polymer such as for examplepolyurethane or a polyolefin such as polyethylene, polypropylene orpolybutene. A polymer based core can be achieved by being injectionmolded or press molded and can be given its shape by plastic molding anddoes therefore not require any abrasive treatment. A polymer based coremay also contain a filler in the form of a particle or fiber of organicor inorganic material, which besides the use a cost reducing materialalso will be used to modify the mechanical characteristics of the core.As an example of such suitable fillers can be mentioned; cellulose orwood particles, straw, starch, glass, lime, talcum, stone powder andsand. The mechanical characteristics that may be changed is for exampleviscosity, thermal coefficient of expansion, elasticity, density, fireresistance, moisture absorption capacity, acoustic properties, thermalconductivity, flexural and shearing strength as well as softeningtemperature.

The upper surface, i.e. the surface that is to be provided with décor,is suitably surface treated before the printing. Such surface treatmentwill then incorporate at least one of the steps, ground coating andsanding. It is also possible to provide the surface with a structurethat matches the décor that is to be applied.

The translucent wear layer is suitably constituted by a UV- or electronbeam curing lacquer such as an acrylic, epoxy, or maleimide lacquer. Thewear layer is suitably applied in several steps with intermediate curingwhere the last one is a complete curing while the earlier ones are onlypartial. It will hereby be possible to achieve thick and plane layers.The wear layer suitably includes hard particles with an average particlesize in the range 50 nm-150 μm Larger particles, in the range 10 μm-150μm, preferably in the range 30 μm-150 μm, is foremost used to achieveabrasion resistance while the smaller particles, in the range 50 nm-30μm, preferably 50 nm-10 μm is used for achieving scratch resistance. Thesmaller particles are hereby used closest to the surface while thelarger ones are distributed in the wear layer. The hard particles aresuitably constituted of silicon carbide, silicon oxide, α-aluminum oxideand the like. The abrasion resistance is hereby increased substantially.Particles in the range 30 mm-150 mm can for example be sprinkled onstill wet lacquer so that they at, least partly, becomes embedded infinished wear layer. It is therefore suitable to apply the wear layer inseveral steps with intermediate sprinkling stations where particles areadded to the surface. The wear layer can hereafter be cured. It is alsopossible to mix smaller particles, normally particle sizes under 30 μmwith a standard lacquer. Larger particles may be added if a gellingagent or the like is present. A lacquer with smaller particles issuitably used as top layer coatings, closer to the upper surface. Thescratch resistance can be improved by sprinkling very small particles inthe range 50 nm-1000 nm on the uppermost layer of lacquer. Also these,so called nano-particles, can be mixed with lacquer, which with isapplied in a thin layer with a high particle content. Thesenano-particles may besides silicon carbide, silicon oxide and α-aluminumoxide also be constituted of diamond.

According to one embodiment of the invention, the translucent wear layeris constituted of one or more sheets of α-cellulose which areimpregnated with melamine-formaldehyde resin. These sheets are joinedwith the core under heat and pressure whereby the resin cures. It is,also in this embodiment, possible to add hard particles with an averageparticle size in the range 50 nm-150 μm. Larger particles, in the range10 μm-150 μm, preferably 30 μm-150 μm is foremost used to achieveabrasion resistance while the smaller of the particles, in the range 50nm-30 μm, preferably 50 nm-10 μm, is used to achieve scratch resistance.The smaller particles is hereby used on, or very close to, the topsurface while the larger particles may be distributed in the wear layer.Also here the particles advantageously are constituted of siliconcarbide, silicon oxide, α-aluminum oxide, diamond or the like of whichdiamond, of cost reasons only is used as particles smaller than 1 μm.The sheets of α-cellulose are hereby suitably pressed together with therest of the surface element in a continuous belt press with two steelbelts. The pressure in the press is hereby suitably 5-100 Bar,preferably 20-80 Bar. The temperature is suitably in the range 140-200°C., preferably 160-180° C. It is also possible to utilize adiscontinuous process where a number of surface elements can be pressedin a so called multiple-opening press at the same time. The pressure isthen normally 20-150 Bar, preferably 70-120 Bar, while the temperaturesuitably is 120-180° C., preferably 140-160° C.

The décor on the surface elements is suitably constituted by a number ofdécor segments with intermediate borders, which borders, on at least twoopposite edges coincides with intended, adjacent surface elements.

It is also desirable to provide the surface elements with a surfacestructure intended to increase the realism of the décor of the surfaceelements. This is suitably achieved by positioning at least one surfacestructured matrix, forming at least one surface structure segment on acorresponding décor segment or number of décor segments on the decoratedsurface of the surface element in connection to the application of wearlayer. This matrix is pressed towards the wear layer whereby this willreceive a surface with structure that enhances the realism of the décor.

When simulating more complex patterns, like wood block chevron patternsor other décors with two or more divergent and oriented décors, it issuitable to use at least two structured matrixes which form onestructure segment each. The structure segments are independent from eachother in a structure point of view. The surface structure segments areintended to at least partly but preferably completely match thecorresponding décor segments of the décor. The surface structuresegments are accurately positioned on the décor side of the surfaceelement in connection to the application of the wear layer, and arepressed onto this whereby the wear layer is provided with a surfacestructure where the orientation of the structure corresponds to thedifferent directions in the décor.

One or more matrixes preferably form the surface of one or more rollers.The surface element is then passed between the roller or rollers andcounter stay rollers, with the décor side facing the structured rollers.The structured rollers are continuously or discontinuously pressedtowards the décor surface of the surface element.

Rollers containing two or more matrixes, are suitably provided with acircumference adapted to the repetition frequency of change of directionin the décor.

It is also possible to apply the structure matrixes on the surface of apress belt. The surface element is then passed between the press beltand a press belt counter stay under continuous or discontinuous pressurebetween the structured press belt and the press belt counter stay.

It is, according to one alternative procedure, possible to have one ormore matrixes form the structure surface of one or more static moldswhich momentary is pressed towards the decorative side of the surfaceelement.

According to one embodiment of the invention, particularlycharacteristic décor segments such as borderlines between simulatedslabs, bars, blocks or the like and also knots, cracks, flaws and grainwhich is visually simulated in the décor, is stored as digital data.Said data is used for guiding automated engraving or pressing tools whenproviding said characteristic décor segments with a suitable surfacestructure, and that said engraving tool or pressing tool is synchronizedvia the predetermined fixing point on the surface element.

The process described in the present application, for manufacturingsurface elements is very advantageous from a logistic point of viewsince the number of steps when achieving a new décor is radicallyreduced. It is, according to the present invention possible to usedigitally created or stored data for directly printing the décor on asurface element by using an ink-jet printer or a photo-static printer.The so-called set up time will thereby be very short, whereby even veryspecial customer requirements may be met at a reasonable cost. It isaccording to the present invention possible to manufacture, for example,a world map in very large format, stretching over a great number ofsurface elements without any disrupting deviations in décor matching, tomainly the same cost as bulk produced surface elements. Since the décormay be handled digitally all the way to the point of being applied tothe surface of the core, set up times will be practically non-existentwhile at the same time a high degree of automation will be practicable.It is also possible to automatically provide the surface elements withidentification and orientation marking which would make the installationof complex décors, like world maps in the example above, much easier.This has so far been impossible.

The décor on the surface elements may be processed as follows;

-   -   i) A segmentation pattern is selected, the segmentation        comprising at least two décor segments on each surface element.        The shape, as seen from above, of the surface element is hereby        selected from the group; triangular, quadratic, rectangular,        heptagonal, pentagonal and octagonal while the shape of the        segments is selected from the group triangular, quadratic,        rectangular, heptagonal, pentagonal, octagonal, circular,        elliptical, perturbed and irregular.    -   ii) A segment décor is then selected for each segment. The        segment décor is selected from the group; digitized and        simulated depiction of different kinds of wood, minerals and        stone, different kinds of fabric, art work and fantasy based        décor.    -   iii) Each selection is made on a terminal where the selection        emanates from a data base and that the selection is visualized        via the terminal.

The décor is preferably achieved by digitization of an actual archetypeor by partly or completely being created in a digital media. Thedigitized décor is preferably stored digitally in order to be used as acontrol function and original, together with control programs andselection parameters, when printing the décor.

The dimensions of the surface to be covered by surface elements aresuitably entered into the terminal and support programs calculate aninstallation pattern. The installation pattern calculation is suitablyalso used for printing an assembly instruction. In order to visualizethe selection the installation pattern calculation is possibly used forprinting a miniaturized copy of the calculated installation with theselected pattern and décor. The dimensions of the surface to be coveredby surface elements are suitably entered into the terminal and supportprograms further calculate décor and segmentation pattern matchingbetween the surface elements.

The selections is preferably also used, together with support programsfor controlling further steps in the manufacturing procedure selectedfrom the group; identification marking, positioning marking, packaging,lacquering, surface embossing, storing and delivery logistics. Analgorithm is suitably used for guiding the positioning of the décorsegments and segmentation pattern so that a décor segment from onesurface element may continue on an adjoining surface element. Thecontrol program is suitably used, together with décor data and selectionparameters, for applying matching identification on the surfaceelements.

Surface elements manufactured as described above are suitably used as afloor covering material where the demands on stability and scratch andabrasion resistance are great. It is, according to the presentinvention, also possible to use the surface elements as wall and ceilingdecorative material. It will however not be necessary to apply thickwear layer coatings in the latter cases as direct abrasion seldom occurson such surfaces.

The invention is described further in connection to an enclosed figure,embodiment examples and schematic process descriptions showing differentembodiments of the invention.

BRIEF DESCRIPTION OF THE DRAWINGS

A full and enabling disclosure of the present subject matter includingthe best mode thereof to one of ordinary skill in the art is set forthmore particularly in the remainder of the specification, includingreference to the accompanying figures, in which:

FIG. 1 is a top perspective view of a surface element according to thedisclosure herein;

FIG. 2 is a flow diagram of a first process scheme; and

FIG. 3 is a flow diagram of a second process scheme.

DETAILED DISCLOSURE

Accordingly, the figure shows parts of a surface element 1 whichincludes an upper decorative layer 2, edges 3 intended for joining, alower side 4 and a supporting core 5. The process is initiated bymanufacturing a supporting core 5 with a desired format and edges 3intended for joining. The supporting core 5 is further provided with anupper side 1′ suited for printing and a lower side 4. The upper side 1′of the supporting core 5 is then provided with a décor 2′ by printing,utilizing an ink-jet printer. The décor 2′ is oriented after apredetermined fixing point on the supporting core 5. The upper side 1′of the supporting core 5 is then provided with a protecting translucentwear layer 2″ through curtain coating. The supporting core 5 isconstituted by particle board or fiber board. The translucent wear layer2″ is constituted by a UV-curing acrylic lacquer which is applied inseveral steps with intermediate curing, of which the last one is acomplete curing while the earlier ones are only partial curing. The wearlayer 2″ also includes hard particles of α-aluminum oxide with anaverage particle size in the range 0.5 μm-150 μm.

A surface structured matrix is positioned and pressed towards the décorside of the surface element 1 before the final curing of the acryliclacquer whereby the surface of the wear layer 2″ receives a surfacestructure 2″ which enhances the realism of the décor 2′.

It is also possible to utilize two or more surface structured matrixes,each forming a structure segment, between which the structure isindependent, which will make it possible to simulate the surfacestructure of, for example, wood block chevron pattern décor.

A supporting polymer and filler based core is manufactured in thedesired format and is provided with an upper side, a lower side andedges provided with joining members, such as tongue and groove. Theupper side of the supporting core is then sanded smooth after which aprimer is applied. A décor is then applied on the upper side by means ofa digital photo-static five color printer. The colors are magenta,yellow, cyan, white and black. The décor is positioned from apredetermined fixing point in form of a corner of the supporting core,while the décor direction is aligned with the long side edge initiatingfrom the same corner.

The basis for the décor is stored as digital data. This digital data hasbeen achieved by digitizing a number of wood grain patterns with adigital camera. A number of rectangular blocks with a fixed width, butof varying length is selected and parted from the digital wood grainpictures. The width of the rectangular blocks is selected so that threeblock widths equal the width of a supporting core. The digital images ofthe wood blocks are then classified after wood grain pattern and colorso that a number of groups are achieved. The groups are; fair wood witheven grain, dark wood with even grain, fair wood with knots and flaws,dark wood with knots and flaws, fair cross-grained wood and finally darkcross-grained wood. Each group contains five different blocksimulations. An algorithm is feed into a computer which is used for theguiding of the printing operation so that the simulated wood blocks isdigitally placed in three longitudinal rows and mixed so that twosimilar wood blocks never is placed next to each other. The algorithmwill also guide the position of the latitudinal borderlines between thesimulated wood blocks so that they are unaligned with more than oneblock width between adjacent rows. It will also guide the latitudinalposition of the borderlines so that it either aligns with the shorteredges of the supporting core or is unaligned with more than one blockwidth. Another printer, also guided by the computer, is utilized forprinting a running matching number on the lower side short side edges.The décor will hereby continue longitudinally over the surface elementsand a perfect matching is obtained when the surface elements are placedin numerical order.

A basic layer of UV-curing acrylic lacquer is then applied by means of aroller. Particles with an average particle size in the range 150 μm isthen sprinkled onto the still wet basic layer, whereby the main layer ofUV-curing acrylic lacquer is applied by spray coating. The two layers oflacquer are then partly cured using UV-light whereby the viscosity ofthe lacquer increases. A top layer of UV-curing acrylic lacquer with anadditive in the form of hard particles with an average size of 2 μm, isthen applied by means of a roller. Hard particles with an average sizeof 100 nm are then sprinkled on top of the wet top layer, whereby thelacquer is partly cured with UV-light so that the viscosity increases.The still soft lacquer is then provided with a structure in the form ofnarrow, small, elongated recesses, simulating the pores of the wood.This will increase the realism of the décor. This is achieved byalternating between two different structured rollers per row ofsimulated wood blocks. The structure of the rollers simulates even woodgrain and cross-grained wood respectively. The rollers are alternatelypressed towards the lacquered surface while it passes. The positioningof the rollers is guided via the digitally stored data used for printingthe décor as well as the fixing point used there.

It is according to one alternative embodiment possible to utilize one ormore static molds with surface structure which momentary is pressedtowards the décor side.

Especially characteristic décor segments such as borderlines betweenslabs, bars, blocks or the like and also knots, cracks, flaws and grainwhich is visually simulated in the décor, is suitably stored as digitaldata. This data is achieved by processing selected parts of thesimulated wood blocks so that guiding data is achieved. Said data isthen used for guiding an automated robot provided with an engraving toolor a press mold which provides the surface of the lacquer with astructure that matches said characteristic décor segments. The operationis also here synchronized via by the predetermined fixing point on thesupporting core.

The lacquer is then completely cured with UV-light to desired strength,whereby the finished surface elements may be inspected by the naked eyeor by a digital camera supported by a computer. The surface elements arethen packed in batches and provided with identification markings.

The process above will make it possible to have a completely customerdriven manufacturing where even very small quantities may be producedwith the same efficiency as bulk manufacturing. Even though only onedécor is described in connection to the process scheme above, it becomesclear to anyone skilled in the art, that a décor is changed very easilyin the process. All of the important steps of the manufacturing such asprinting, structuring, inspection, packaging and identification markingmay be controlled and supervised by central processing data. This willmake it logistically possible to manufacture customer designed décors.Such a process is exemplified as follows;

The customer utilizes a database via Internet or at a local dealer. Itis also possible for another operator utilize a database. The databasecontains samples and/or reduced resolution copies of a great variety ofstandard décors which can be combined after predetermined parameters.

The parameters may, for example, concern a single surface element where,for example, chevron pattern, diamond pattern and block pattern may bethe choices of décor segmentation. It will here be possible to select aset of different simulations to randomly or by selected parameters fillthe segments, for example, marble, birch and mahogany. The customer mayalso add an inlay from a design of his own which is digitized andprocessed, preferably automatically, to a desired format and resolution.

The parameters may alternatively include décor segments that require thespace of several surface elements, for example a map over the world. Theparameters may here further include fading of the larger design to asurrounding décor, surrounding frame of other décor etc.

The customer enters the measurements of the surface that is to becovered by the surface elements. The customer then makes selections fromthe database and is able to see his selection as a completed surface,either on screen or by printing. The visualization program used, issuitably also used for calculating installation pattern and presentinginstallation instructions with identification numbers on surfaceelements and where to cut the elements in order to make a perfect match.The surface elements may also be provided with removable matching lineson the decorative side making matching of décor between adjacent rowseasier. The customer or dealer may then confirm his order via electronicmail where the pattern and décor is reduced to a code sequence and theorder can be the direct input to the computer guiding the manufacturingprocess as described above. The customer and/or dealer data follows themanufacturing process all the way to packaging and a fully customerguided manufacturing process is achieved.

A supporting fiber board based core is manufactured in the desiredformat and is provided with an upper side, a lower side and edges. Theupper side of the supporting core is then sanded smooth after which awhite primer is applied. A décor is then applied on the upper side bymeans of a digital ink-jet four color printer. The colors are magenta,yellow, cyan and black. The décor is positioned from a predeterminedfixing point in form of a corner of the supporting core, while the décordirection is aligned with the long side edge initiating from the samecorner.

The basis for the décor is stored as digital data. This digital data hasbeen achieved by digitizing a number of wood grain patterns with adigital camera. A number of rectangular blocks with a fixed width, butof varying length are selected and parted from the digital wood grainpictures. The width of the rectangular blocks is selected so that threeblock widths equal the width of a finished surface element. The digitalimages of the wood blocks are then joined digitally to form arectangular surface of a specified size, for example, 200.times.1200 mm.A selected amount of such combinations of different blocks are designedas described above so that a number of slightly different rectangularsurfaces are achieved. The printer, or preferably a set of printers arepositioned so that a desired number of rectangular décor surfaces with aspecified intermediate distance is printed on the supporting core. Theintermediate distance between the rectangular surfaces is the distanceneeded for parting and molding of edges. The décor printer or printersare also used for printing fixing points at predetermined positions.Another printer, also guided by the computer, is utilized for printingan identity code on the lower side of each intended finished surfaceelement.

A basic layer of UV-curing acrylic lacquer is then applied by means ofrollers. Particles with an average particle size in the range 75 μm isthen sprinkled onto the still wet basic layer, whereby a top layer ofUV-curing acrylic lacquer with an additive in the form of hard particleswith an average size of 2 μm, is applied by means of a roller. Hardparticles with an average size of 100 nm are then sprinkled on top ofthe wet top layer, whereby the lacquer is partly cured with UV-light sothat the viscosity increases. The still soft lacquer is then providedwith a structure in the form of narrow, small, elongated recesses,simulating the pores of the wood. This will increase the realism of thedécor. This is achieved by pressing rollers towards the lacqueredsurface while it passes. The positioning of the rollers are guided viathe digitally stored data used for printing the décor, as well as thefixing point used there when more complex and completely matchingsurface structures as described together with process scheme 1 isdesired.

The lacquer is then completely cured with UV-light to desired strength,whereby the finished surface element is cut into the predeterminedformats which are provided with edges with joining functionality aremolded by milling. The cutting and edge molding process is positionedfrom fixing point printed close to the décor. The surface elements maythen be inspected by the naked eye or by a digital camera supported by acomputer. The surface elements are then packed in batches and providedwith identification markings.

It is, according to an alternative procedure in the process, possible tocut and mold the edges at an earlier stage in the process. It issuitable to apply and cure a protecting layer of lacquer on top of theprinted décor followed by cutting and molding of the edges. Theremaining and main part of the wear layer is then applied as describedin connection to process scheme 1 or 2 above.

The process above will make it possible to have a customer initiatedmanufacturing where even very small quantities may be produced with thesame efficiency as bulk manufacturing. Even though only one décor isdescribed in connection to the process scheme above, it becomes clearanyone skilled in the art, that decors is changed very easily in theprocess. All of the important steps of the manufacturing such asprinting, structuring, inspection, packaging and identification markingmay be controlled and supervised by central processing data.

The invention is also described through embodiment examples.

EXAMPLE 1

A supporting core of medium density fiber board was sanded smooth. Alayer of primer lacquer was applied on top of the fiber board. Theprimer was cured after which a décor was printed on top of the primer.

The build up of a wear layer was then initiated by applying 30 g/m² ofUV-curing acrylic lacquer by means of roller coating. 20 g/m² of hardparticles made of α-aluminum oxide with an average particle size of 70μm were sprinkled on the still sticky lacquer. The lacquer was thenexposed to a predetermined energy amount of UV-light so that it curedonly partly and the viscosity was increased. Another 30 g/m² ofUV-curing acrylic lacquer was then roller coated onto the alreadyapplied layer after which another 20 g/m² of α-aluminum oxide particleswith an average particle size of 70 μm were sprinkled on the stillsticky second coating. The lacquer was then exposed to a predeterminedenergy amount of UV-light so that it cured only partly and the viscositywas increased. Three layers of UV-curing acrylic lacquer were thenapplied by roller coating with intermediate partial curing as above.Each of the three layers had a surface weight of 20 g/m². The hardparticles were completely embedded in the lacquer after the three layerswere applied and a plane upper wear layer surface was achieved.

A top coating procedure was then initiated. A first layer of UV-curingacrylic topcoat lacquer was applied by means of a roller coater on topof the previous, partly cured, layers. The topcoat lacquer contained 10%by weight of hard particles of α-aluminum oxide with an average particlesize of 10 μm. The first layer was applied to a surface weight of 10g/m². The topcoat lacquer was then exposed to a predetermined energyamount of UV-light so that it cured only partly and the viscosity wasincreased. A second layer of the topcoat lacquer was then applied andpartly cured as described above. The wear layer was then provided with asurface structure by means of a surface structured roller. A third layerof the topcoat formulation was then applied on top of the structuredwear layer. Also the third layer of top coat was applied to a surfaceweight of 10 g/m². The wear layer was then exposed to a predeterminedenergy amount of UV-light so that it cured completely.

The wear layer was then tested for abrasion resistance according to ISO4586/2-88, where an IP value of 7100 turns was obtained. An IP value of7100 turns is fully sufficient for floor covering materials with mediumto heavy traffic like hotel lobbies, hallways and the like.

EXAMPLE 2

A supporting core of medium density fiber board was sanded smooth. Alayer of primer lacquer was applied on top of the fiber board. Theprimer was cured after which a décor was printed on top of the primer.The build up of a wear layer was then initiated by applying 30 g/m² ofUV-curing acrylic lacquer by means of roller coating. 20 g/m² of hardparticles made of α-aluminum oxide with an average particle size of 70μm were sprinkled on the still sticky lacquer. The lacquer was thenexposed to a predetermined energy amount of UV-light so that it curedonly partly and the viscosity was increased. Another 30 g/m² ofUV-curing acrylic lacquer was then roller coated onto the alreadyapplied layer after which another 20 g/m² of α-aluminum oxide particleswith an average particle size of 70 μm were sprinkled on the stillsticky second coating. The lacquer was then exposed to a predeterminedenergy amount of UV-light so that it cured only partly and the viscositywas increased. Three layers of UV-curing acrylic lacquer were thenapplied by roller coating with intermediate curing as above. Each of thethree layers had a surface weight of 20 g/m². The hard particles werecompletely embedded in the lacquer after the three layers were appliedand a plane upper wear layer surface was achieved. Also the uppermost ofthe three layers of lacquer was cured to a desired viscosity.

A second décor layer was then printed on top of the wear layer. Thesecond décor layer, which was identical to the first décor closest tothe core, was oriented and positioned so that it completely matched thefirst décor.

The build up of an upper wear layer was then initiated by applying 30g/m² of UV-curing acrylic lacquer by means of roller coating. 20 g/m² ofhard particles made of α-aluminum oxide with an average particle size of70 μm were sprinkled on the still sticky lacquer. The lacquer was thenexposed to a predetermined energy amount of UV-light so that it curedonly partly and the viscosity was increased. Another 30 g/m² ofUV-curing acrylic lacquer was then roller coated onto the alreadyapplied layer after which another 20 g/m² of α-aluminum oxide particleswith an average particle size of 70 μm were sprinkled on the stillsticky second coating. The lacquer was then exposed to a predeterminedenergy amount of UV-light so that it cured only partly and the viscositywas increased. Three layers of UV-curing acrylic lacquer were thenapplied by roller coating with intermediate curing as above. Each of thethree layers had a surface weight of 20 g/m². The hard particles werecompletely embedded in the lacquer after the three layers were appliedand a plane upper wear layer surface was achieved.

A top coating procedure was then initiated. A first layer of UV-curingacrylic topcoat lacquer was applied by means of a roller coater on topof the previous, partly cured, layers. The topcoat lacquer contained 10%by weight of hard particles of α-aluminum oxide with an average particlesize of 10 μm. The first layer was applied to a surface weight of 10g/m². The topcoat lacquer was then exposed to a predetermined energyamount of UV-light so that it cured only partly and the viscosity wasincreased. A second layer of the topcoat lacquer was then applied andpartly cured as described above. The wear layer was then provided with asurface structure by means of a surface structured roller. A third layerof the topcoat formulation was then applied on top of the structuredwear layer. Also the third layer of top coat was applied to a surfaceweight of 10 g/m². The wear layer was then exposed to a predeterminedenergy amount of UV-light so that it cured completely.

The wear layer was then tested for abrasion resistance according to ISO4586/2-88, where an IP value of 13500 turns was obtained. An IP value of13500 turns is fully sufficient for floor covering materials withheavier traffic like airports, railway stations and the like. The secondlayer of décor and wear layer will add abrasion resistance withouthaving obtained an unwanted hazy effect in the décor.

EXAMPLE 3

A supporting core of medium density fiber board was sanded smooth. Alayer of primer lacquer was applied on top of the fiber board. Theprimer was cured after which a décor was printed on top of the primer.

The build up of a wear layer was then initiated by applying 15 g/m² ofUV-curing acrylic lacquer by means of roller coating. 20 g/m² of hardparticles made of α-aluminum oxide with an average particle size of 70μm were sprinkled on the still sticky lacquer. The lacquer was thenexposed to a predetermined energy amount of UV-light so that it curedonly partly and the viscosity was increased. One layer of UV-curingacrylic lacquer was then applied by roller coating and was partiallycured as above. The layer had a surface weight of 40 g/m². The hardparticles were embedded in the lacquer after the layer of lacquer wasapplied and a mainly plane upper wear layer surface was achieved.

A top coating procedure was then initiated. A first layer of UV-curingacrylic topcoat lacquer was applied by means of a roller coater on topof the previous, partly cured, layers. The topcoat lacquer contained 10%by weight of hard particles of α-aluminum oxide with an average particlesize of 10 μm. The first layer was applied to a surface weight of 10g/m². The topcoat lacquer was then exposed to a predetermined energyamount of UV-light so that it cured only partly and the viscosity wasincreased. The wear layer was then provided with a surface structure bymeans of a surface structured roller. A second, final layer of thetopcoat formulation was then applied on top of the structured wearlayer. Also the second layer of top coat was applied to a surface weightof 10 g/m². The wear layer was then exposed to a predetermined energyamount of UV-light so that it cured completely.

The wear layer was then tested for abrasion resistance according to ISO4586/2-88, where an IP value of 3100 turns was obtained. An IP value of3100 turns is fully sufficient for floor covering materials with lighttraffic like bedrooms, living rooms and the like.

The invention is not limited to the embodiments shown as these can bevaried in different ways within the scope of the invention. It is forexample possible to use so-called overlay sheets of α-celluloseimpregnated with thermosetting resin instead of acrylic lacquer in theprocess described in connection to process scheme 1 and in particular inthe process described in connection to process scheme 2. These sheets ofα-cellulose which are impregnated with melamine-formaldehyde resin arejoined with the supporting core through heat and pressure, whereby theresin cures. The wear resistance may also in this embodiment be improvedby adding hard particles in the range 50 nm-150 μm to the wear layer.

What is claimed is:
 1. A process for manufacturing of surface elementswherein said surface elements comprise a decorative upper layer and asupporting core, the process comprising: manufacturing a supporting corehaving a format essentially equaling a desired end user format andprovided with an upper side and a lower side; providing a ground coatingon the supporting core; applying a digitally printed décor comprisinginks of at least four colors directly on top of the ground coating by anink-jet type printer, said four colors comprising one or more colorsdifferent from cyan, magenta, yellow and black, said digitally printeddecor being one of wood or mineral; and providing and curing an at leastpartly translucent wear layer on the upper side of the supporting core.2. The process of claim 1, said process further comprising providingsaid surface elements with a surface structure intended to increaserealism of the digitally printed decor.
 3. The process of claim 2,wherein said structure is directed in accordance with alignment of theprinted décor.
 4. The process of claim 2, wherein said surface elementsare provided with said surface structure prior to applying saiddigitally printed decor.
 5. The process of claim 1, wherein thesupporting core is manufactured at least using particles of inorganicmaterial.
 6. The process of claim 5, wherein said particles of inorganicmaterial are selected from the group consisting of stone powder, lime,talcum, glass and sand.
 7. The process of claim 1, wherein said one ormore colors different from cyan, magenta, yellow and black at leastinclude a spot color.
 8. The process of claim 1, wherein the groundcoating comprises a layer of white primer lacquer.
 9. The process ofclaim 1, wherein the surface element is rectangular with two pairs ofparallel opposite edges, wherein the printed décor is aligned with atleast one edge.
 10. The process of claim 1, wherein the printed décorhas a resolution of 300 dots per inch (dpi) or more.
 11. The process ofclaim 1, wherein the four colors at least include magenta, yellow andblack.
 12. The process of claim 1, wherein said one or more colorsdifferent from cyan, magenta, yellow and black at least include white.13. The process of claim 1, wherein said one or more colors differentfrom cyan, magenta, yellow and black at least include light magenta. 14.The process of claim 1, wherein said digitally printed decor includes awood grain pattern comprising at least one of visually simulated knots,cracks, flaws and grain.
 15. The process of claim 1, wherein said atleast partly translucent wear layer comprises hard particles of siliconoxide.
 16. A process for manufacturing of surface elements wherein saidsurface elements comprise a decorative upper layer and a supportingcore, the process comprising: manufacturing a supporting core having aformat essentially equaling a desired end user format and provided withan upper side and a lower side; providing a white ground coating on thesupporting core; applying a digitally printed décor comprising inks ofat least four colors directly on top of the ground coating by an ink-jettype printer, said four colors comprising one or more spot colorsdifferent from cyan, magenta, yellow and black, said digitally printeddecor being one of a wood grain pattern, a marble pattern and a granitepattern and having a resolution of 300 dots per inch (dpi) or more;providing and curing an at least partly translucent wear layer on theupper side of the supporting core; and providing said surface elementswith a surface structure to increase realism of said digitally printeddecor, wherein said surface elements are provided with said surfacestructure prior to applying said digitally printed decor.
 17. Theprocess of claim 16, wherein said digitally printed decor includes awood grain pattern comprising at least one of visually simulated knots,cracks, flaws and grain.
 18. The process of claim 17, wherein saidsurface structure is in a form of narrow, small, elongated recesses,simulating pores of wood.
 19. The process of claim 16, wherein said atleast partly translucent wear layer is a wear layer comprising siliconoxide.